The module partially disables the store functionality to make it fit businesses selling one product only (for example a book, some software or some service).
It turns homepage into the product details page so that your store visitors see the product info as soon as they come to your store. Categories block, search block, and breadcrumbs are disabled as unnecessary. ‘Add to cart’ button is changed to ‘Buy’ button. Also, the module can be set so, that when customers make a purchase they skip cart preview page and are forwarded directly to the checkout page.
You may have many products in your catalog in the admin area, but only the first active one will be displayed on the storefront.
‘One product’ module is not compatible with the following modules: Product Advisor, Bestsellers, Previous and Next product, Product Comparison, Product Filter, Related Products, Add to Cart Popup, because using these modules together is useless.